twister: footprint: Improve command-line arguments

Improve Twister command line arguments for memory footprint:

 * group and order footprint arguments meaningfully,
 * clearer help descriptions,
 * resolve logical inconsistences for combinations of arguments,
   in particular:
   `--last-metrics` now forces `--enable-size-report`,
   `--show-footprint` now controls only detailed log output of
       footprint deltas in comparison modes.
 * align twister tests accordingly.

Signed-off-by: Dmitrii Golovanov <dmitrii.golovanov@intel.com>